Considerable efforts have been made to develop debridement preparations that are capable of distinguishing between viable and non-viable tissue. These debridement preparations make it possible to remove the devitalized tissue without surgery. Non-surgical debridement is desirable in virtually all disease processes where topically devitalized tissue needs to be removed from the viable organism such as decubitus ulcers, pressure necroses, incisional, traumatic, and pyogenic wounds, and ulcers secondary to peripheral vascular disease.
One area of debridement research that has attracted considerable attention is the use of proteolytic enzymes and other chemicals to effect the early debridement of eschar tissues resulting from burns. Devitalized burn tissue is an excellent culture medium for opportunistic infections in burn patients. Septicemia resulting from infections is the proximate cause of death for the majority of severely burned patients. Intensive investigations with chemical agents such as tannic acid, salicylic acid, and pyruvic acid as well as proteolytic enzymes such as papain, pinguinain, trypsin, and streptokinase have not led to satisfactory debridement. Chemical agents were found to cause further injury to already damaged tissue. Proteolytic enzymes were found to be too slow and to have toxic side effects or to attack viable tissue as well as devitalized tissue.
However, several enzyme preparation from bromelain-stem extract have been found to selectively remove eschar. Hydrated bromelain powder and crude extract were initially employed to remove eschar tissue with mixed results. Purified enzyme isolated from the bromelain stem extracts have proven to be effective in the debridement of eschar tissue. For example, Debridase (described in U.S. Pat. No. 4,329,430), Ananain and Comosain (described in EPA 313346A2) were all purified from bromelain stem extracts for use in debridement. With the extensive research that had been performed to isolate debridement enzymes from bromelain stem extracts it had been thought that all of the effective debridement enzymes in bromelain stem extracts had been already identified and isolated.
However, the present invention is directed to a novel debridement enzyme derived from bromelain stem extracts and methods for extracting and utilizing this enzyme to remove eschar tissue.